Shop-drawing package lists mention sealant data. This page explains how to read the letters before you approve them.
Three different claims
- Compatibility: materials in contact do not chemically attack each other under the tested conditions
- Adhesion: the sealant bonds adequately to the named substrate under the tested conditions
- Substrate / finish approval: the specific finish, coating, or glass edge condition was included in the test or approval language
A letter that only addresses compatibility is not automatically an adhesion approval for every finish on the elevation.
Generic letter anatomy
GENERIC TEMPLATE ONLY. Not a real manufacturer letter. Not project evidence. Replace with current manufacturer documents on each job.
| Letter field | What to verify | Fail signal |
|---|---|---|
| Date and revision | Still current for the products being installed | Years-old letter for discontinued products |
| Sealant product exact name | Matches the specified / submitted sealant | Brand family only, wrong product line |
| Contact materials listed | Glass, interlayer, gaskets, finishes actually used | Missing coated glass or anodize note |
| Claim type | Compatibility, adhesion, or both, stated clearly | Vague "approved for use" without claim type |
| Joint design / thickness limits | Within project joint design | No limits stated when the detail is atypical |
| Surface prep requirements | Callable in the field | Prep omitted but adhesion claimed |
| Exclusions | Read the footnotes | Excludes the exact coating you planned |
Submittal checklist
- Letter attached for each sealant-to-substrate pair that the detail requires
- Product names match the glazing and sealant submittals exactly
- Finish and glass coating conditions covered or separately tested
- Structural silicone applications (if any) follow the structural silicone design path required by the project
What letters do not cover
Letters do not replace joint design, workmanship, or water-test acceptance. They do not approve a different sealant brand by implication. They do not waive product-approval requirements for the fenestration system.
How to ask for letter review
Send details, glass makeup, finish codes, and the proposed sealant products. ACG: (772) 486-7711. FL CGC #1531993.
Frequently Asked Questions
What is the difference between silicone compatibility and adhesion letters?
Compatibility addresses chemical interaction between materials. Adhesion addresses bond to a named substrate under tested conditions. A letter may cover one, both, or neither for your exact finish.
Can I reuse a letter from a previous job?
Only if the exact products, substrates, and conditions match and the letter is still accepted by the manufacturer and the design team. Re-verify dates and product names.
Does a compatibility letter approve structural silicone design?
Not by itself. Structural silicone applications follow the project structural-glazing requirements and manufacturer structural guidelines.
What should a GC attach for sealant review?
Details, glass and finish IDs, proposed sealant product data, and any existing manufacturer letters for those exact combinations.